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IntroductionThe fifth largest moon in the solar system, Earth's moon is the only place beyond Earth where humans have set foot. The brightest and largest object in our night sky, the moon makes Earth a more livable planet by moderating our home planet's wobble on its axis, leading to a relatively stable climate. It also causes tides, creating a rhythm that has guided humans for thousands of years. The moon was likely formed after a Mars-sized body collided with Earth.

Earth's only natural satellite is simply called "the moon" because people didn't know other moons existed until Galileo Galilei discovered four moons orbiting Jupiter in 1610. Explore Earth's Moon ›

Ten Things to Know About Earth's Moon

Ten Things to Know About Earth's Moon

1

Small Companion

If the Sun were as tall as a typical front door, Earth would be the size of a nickel and the Moon would be the size of a green pea.

2

Natural Satellite

The Moon is Earth's satellite and orbits the Earth at a distance of about 384 thousand km (239 thousand miles) or 0.00257 AU.

3

One-Sided View

The Moon makes a complete orbit around Earth in 27 Earth days. The Moon keeps the same side, or face, towards Earth during its orbit.

Viewing Copernicus

4

Can Stand on It

The Moon is a rocky, solid-surface body with much of its surface cratered and pitted from impacts.

5

Bring a Spacesuit

The Moon has a very thin and tenuous atmosphere called an exosphere. It is not breathable.

6

Moonless

The Moon has no moons.

7

Ringless

The Moon has no rings.

8

Many Visitors

More than 100 spacecraft been launched to explore the Moon. It’s the only celestial body beyond Earth visited by human beings.

9

Potential for Life?

The Moon's weak atmosphere and its lack of liquid water cannot support life as we know it.

10

Moonwalkers

Astronauts brought back a total of 842 pounds (382 kilograms) of lunar rocks and soil to Earth. We are still studying them.

Apollo 11 Bootprint

Did You Know?

Did You Know?

A Steady HandThe moon is more than a pretty accessory in our night sky. It stabilizes Earth's wobble, which led to a more stable climate and probably helped life evolve. The moon also guides the ebb and flow of Earth's oceans.

Free MoonAstronauts planted six American flags on the moon, but that doesn't mean the United States owns it. An international law written in 1967 prevents any single nation from owning planets, stars or any other natural objects in space.

Super MoonOnce a year the full moon appears 14 percent larger than usual. This happens when the moon's egg-shaped (elliptical) orbit reaches the closest point to Earth (perigee). A full moon at perigee equals what we call a super moon.

Robots RocksThree Soviet robotic missions collected about 11 ounces (320 grams) of lunar soil and returned them to Earth for study. The first - Luna 16 - was the first robotic sample return from space.

Flip SideHumans have studied the moon for thousands of years, but we didn't see its far side until a spacecraft got there in 1959. The moon rotates once on its axis in about the same time it orbits Earth so the same side faces us at all times.

Night LightThe moon is the brightest and largest feature in the night sky. Venus is second.

Cold StorageRegions of the moon's poles are extremely cold: about -457.6 degrees Fahrenheit (-272 degrees Celsius). Some parts of lunar polar crater never get sunlight. We've seen signs of water ice in those shadowed areas.

Moon RocksApollo astronauts brought back a total of 842 pounds (382 kilograms) of lunar samples to Earth for study. We are still studying them.

FootholdThe moon is the only place beyond Earth where humans have set foot.Pop Culture

Pop Culture

Our lunar neighbor has inspired stories since the first humans looked up at the sky and saw its gray, cratered face. Some observers saw among the craters the shape of a person's face, so stories refer to a mysterious "man in the moon." Hungrier observers compared its craters to cheese and dreamed of an entire sphere made of delicious dairy products.

Jules Verne's 1865 novel From the Earth to the Moon is often credited with inspiring real-life rocket pioneers such as Robert Goddard and Hermann Oberth. While the novel is science fiction, Verne made a few interesting and accurate predictions.

The United States would launch the first manned vehicle to go to the moon. The shape and size of the vehicle would closely resemble the Apollo command/service module spacecraft.

The number of men in the crew would be three.

A competition for the launch site would ensue between Florida and Texas which actually was resolved in Congress in the 1960s with Kennedy Space Center as the Flordia launch site and Houston, Texas, as the Mission Control Center.

A telescope would be able to view the progress of the journey. When Apollo 13 exploded, a telescope at Johnson Space Center witnessed the event which happened more than 200,000 miles from Earth.

The Verne spacecraft would use retro-rockets which became a technology assisting Neil Armstrong and his crewmates in their journey to the Moon.

Verne predicted weightlessness although his concept was slightly flawed in thinking it only was experienced at the gravitational midpoint of the journey (when the Moon and Earth gravity balanced).

The first men to journey to the Moon would return to Earth and splash down in the Pacific Ocean just where Apollo 11 splashed down in July of 1969 one hundred and six years after the initial publication of the novel.

The moon made its film debut in a 1902 black and white silent French film called Le Voyage Dans la Lune (a trip to the moon). And a year before astronauts walked on the moon, 2001: A Space Odyssey (1968) told the story of astronauts on an outpost on the moon. Decades later, it is still widely regarded as the best science fiction movie ever made.

In reality, while we do not yet have a moon colony, spacecraft have left lots of debris on the lunar surface, and astronauts have planted six American flags on the moon. But that doesn't mean the United States has claimed it; in fact, an international law written in 1967 prevents any single nation from owning planets, stars, or any other natural objects in space.